Gear shift mechanism



Nov. 9, 1937. D. MAKER ET AL ,2,098,708

GEAR SHIFT MEGHANSM Filed Jan. 27, 195e 2 sheets-sheet 1 N0v.9,1,937. D. L. MAKER ETAL 12,098,708

GEAR SHIFT MECHANI SM Patented Nov. 9, 1937 UNITED STATES GEAR SHIFT MECHANISM Dewey L. Maker and Harry E. Fidler, Detroit,

Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application January 27, 1936, Serial No. 60,919

Claims.

This invention relates to change speed mechanism such as is used on vehicles. It has been designed as an improvement in the control mechanism by which the several speed ratios between 5 the input and output shafts are obtained.

An object of the invention is to provide a simple, compact, inexpensive mechanism by which the driving ratio may be readily changed.

Other and more specific objects will appear from the following description.

In the accompanying drawings:

Fig. 1 is a view in side elevation, the transmission housing being broken away.

Fig. 2 is an inverted plan view of the housing cover with parts associated therewith.

Fig. 3 is a view as seen from line 3'-3 of Fig. 4.

Fig. 4 is a transverse section substantially on line 4-4 of Fig. 1.

Fig. 5 is a view as seen from line 5-5 of Fig. 1.

Figs. 6, 7, and 8 are plan views of relative movable parts to illustrate several operative positions.

Fig. 9 is a detail in perspective.

Referring by numerals to the drawings, there is shown in Fig. 1 the clutch housing I I of a motor vehicle to the rear of which and integral therewith is a change speed transmission housing I3.

The transmission mechanism includes an input shaft I5 journaled in the housing I3 at Il and an output shaft I9 journalel at 2 I. The input shaft has a gear 23 in constant engagement with a gear 25 on a countershaft 2l. Adjacent gear 23 the input shaft has clutch teeth 29 engageable with teeth 3l on a gear S3 slidable but non-rotatable on the inner end of the output shaft I9. A synchronizing clutch is marked by numeral 35. When gear 33 is rnoved to the left, its teeth 3i lock with teeth' 29, subsequently to synchronism being effected by friction clutch 35, whereupon the input and output shafts are locked for rotating together-the fourth or high speed drive for this transmission. On the countershaft is a gear 3l adapted to engage gear 33 when the latter is moved to the right from its position shown. The engagement of these teeth provides the rst or low speed through the instrumentality of gear trains 23-25 and 35i- 33. Gear 33 has a collar 39 to be engaged by a fork il to make the aforesaid shifts.

Freely rotatable on the output shaft adjacent bearing 2i is a gear 43. It is in constant mesh with a countershaft gear 95. Gear 4.3 has a hub with clutch teeth 4'! adapted to engage teeth 49 on a gear 5 I slidably but not rotatably mounted on the output shaft. Gear 5I may be moved to the right to engage teeth 49 and 41 subsequently to the action of a synchronizing clutch 53 to thereby lock gear 43 to the output shaft. This provides a third speed or high intermediate drive through the instrumentality of gear trains 23-.25 vand 45 43. A second speed or low intermediate is accomplished by sliding gear 5I to the left and into mesh with countershaft gear 55, the drive then being through gear trainsw23e-25 and 55-5I. Gear 5I has a collar 5l engaged by a fork 59 for making these shifts.

Reverse driving makes use of a straddle idler element 6I having tvlo gears 53 and 65. A collar 61 is engaged by the lug on the end of a lever 69. Reverse driving is accomplished by rotating the lever 69 to move gear 63' intoV mesh with gear 33 and a gear into mesh with another gear 'II onv the countershaft. This drive employs gear trains 23-25, 'II-65, and 63-33.

The mechanism for shifting the gears employs a shift lever 'I3 pivoted in a dome 'I5 of cover ,'I'I. In the top of the dome is inserted a rubber cylindrical block or seal 19. A pin 8| extends through the rubber block and is rotatably supported in apertures 83 extending through the dome, the aperture lying in the line transversely of the longitudinal axis of the housing. The pin ex-v tends through a cylindrical member Sli rotatable in a spherical part 95 of the lever, the latter located in a similarly shaped opening in the rubber block. The lateral sides ofthe part 85 have slots 8l to accommodate the pin BI as member 8 rotates in 85. By this construction the lever is supported for universal movements and the rubber serves to prevent leakage and also prevents noise. An enlargement 89 on the lower end of the shift lever enters a hole SI in a lever 93. To reach the lever 93 the lower end of the shift lever extends through a triangular shaped opening in a plate 95 shown in perspective in Fig. 9, one side 96 of the opening being positioned toward the front of the plate, and an apex 98 being toward the rear. The plate 95 has two closed slots 9i adjacent one side and extending transversely. Adjacent the other sides are two open slots 99. Tongues IUI in axial alignment are turned down from the ends of slots 91. Midway between the Ysides of the plate and at both front and rear ends the material of the plate is depressed to form channels as at |93 terminating in walls H15. These channels cooperate with like channels IU'I formed in the cover plate 11. The channels house coil springs |09 normally engaging the shoulders |05 and similar shoulders in the channel of the cover plate. The plate also has other tongues` III and II3 turned down from its side edges, which tongues plate and are held by nuts |2I.

pins, four in number, extend through the slots 91 and 99, their heads being Vbelow the plate 95. The springs |09 resist transverse movement of the plate. f The pins extend through the coverk The lever 93 lies f adjacent the lower face of plate 95.. At its ends are pins movable in slots I I and I I1 and extending through and below the lever for a purpose to be described.

The housing has two shift rods or rails |22 and I23. These rails are axially slidable in therhousing.V Rail |22 Vcarries fork 4I, thefork being secured by a set screw |25.

|21 secures fork 59 to rail |23. Fork 4I-the fork for shifting gear 33 to effect direct or fourth speed and low or first speedis positioned byits rail V|22 beneath plate 95. When Vfork 4| is in its mid position the tongue I registers with a trans;

verse slot 3| Vin the top of the fork. This slot` is also, adapted to be engaged by the pin |33 projecting from the end Vof lever 93 so that fore and aft movement of this pin may reciprocate the fork.

v tween these lugs and the lug II3. 35

Y Fork 59 has a head elongated as at |35-.so as to engage both lugs IIJI when the relative positions of this fork and the plate 95 permit it. In the other position of relative transverse adjustment the ends Yof its head are free to slide axially be- This fork too has its head formed with a transverse slot |31 to be engaged by apin |35 projecting from the lever 93. It will be seen that pin |33 in addition to entering slot I3| of the high speed forkV also extends above the lever 93 and enters slot |I5 of plate 95, and that pin, |35 similarly operates inv slot I I1 as well as in the slot |31 of fork 59.. Y

To aid in understanding the oper-ation it may be'well to describe more particularly the shape of slots I|5 and |I1. Slot II5 has a central transverse region having an outer part II5a and. an inner part II5b. It has -a forward 'divergent' partV II5c and a rearward divergent part |I.5d. Slot ||1 has a central transverse region with an outer part Illa and an inner part |I1b. It has a forward divergent part I-I1c and a rearward divergent part II1d.

Fig. 2 shows the parts in their neutral position. It should be explained'that the head of fork 4| is positioned sufficiently inward from the edge of plate 95 so that lug |-I| is not in the Vslot |3I. In this way the fork is free to move fore and aft as far as this lug is concerned. Similarly theV head of fork- 59 is normally disposed out- Wardly from between lugs IUI. The lever pins |33 and I 35 extend below the lever 93 into the fork slots and also, above the lever, they enter the mid portion Vof the slotsV ||5.and I|1.as shown.. When'leverf93 is so positioned the lever 13 is incapable ofvmoving it forwardly or -rearwardly because the pins |33 and |35 engage the four corner obstructions as shown.A If it` be desired to vshift .into `low or first speed the shift leverV 13 is roekedtransversely so that its end Y 9| moves lever 93 transversely. The movement Similarly a set screwv carrying gear 33 to its low speed position in mesh with gear 31. In this oper-ation fork 59 cannot be moved from its neutral position because pin |35, located in the slot of fork 59, slides along the wall of slot II1a and is unable to move rearwardly. The position of parts for low speed is shown by'dotted lines in Fig. 7.

For second speed, lever 13 is returned to theV knob end of lever 13 from Vfirst speed to second speed isA almost rectilinear.

For third speed, lever 93 again returnsy to normal as in Fig. 2. A slight transverse movement of lever 93 moves pin |33 into slot |I`5a after which pin |35 is moved rearwardly inslot II1d. This is shown by Vdotted lines in Fig'. 6. A return to the position from which thirdv speed was effected and a continued'forward 'movement of lever 93 brings it to the dot and dash position of Fig. 7, which corresponds to the fourth or highest speed position of thetransmission, the pin |33 moving in slot |I5c."

In the case of'each shift one pin, |33 Vor |35, whichV is to move a fork, has a movement which is mainly longitudinal but, owingto the angular speeds.Y Between second speed and third speedthere is a transverse movement of the lever 95 and of the knob of lever 13, of course.

For reverse shifting there is the lever 69 pivoted at I4! and engaging by its lower end the collar 61 of the reverse idler. The upper end of lever 69 is received in a notch 43 in the lower edge of side |45 of a U-shaped bar |41. This b-ar has its end arms provided with aligned 4apertures as at I 49 for slidingly supporting the U- shaped baron rail |23. One of the end arms is extended as :at |5I and has a slot |53 to straddle rail |22. The upper edge of side |45 has a. notch |55 normally engaged by tongue II 3 of plate 95, whereby the U-shaped bar may not reciprocate on the rails and whereby no shift into reverse may occur. However, after the lever 93 is movedl bodily in a transverse direction, downwardly in Fig. 2, to its limit of movement relative to plate 95, it may be moved further together with theinnermost part ||5b of slot ||5, longitudinal movement of lever 13 will swing lever 93 and its pin |35 will reciprocate the U-shaped bar |41. This rocks lever 69 and slides the idler 6| and the transmission is then in reverse.

The bar |41 is provided with openings |59 to receive a detent ball |53 projected by a spring |65 located in a threaded plug |61 in the side of the housing. The openings |59 correspond with the neutral and active positions of bar |41. Spring pressed balls |59 are mounted in the cover to engage suitable openings |1| in the plate 95 corresponding to forward speed and reverse speed of the transmission. Spring pressed balls |13 are shown as used to engage notches |15 in the forward speed rails, these notches corresponding to neutral and yactive positions of the shifting rail forks as is usual.

The operation is as follows: The arrangement has been designed for a right-hand drive vehicle, the driver being seated at the right side of the mechanism. To shift from neutral to first speed he shifts the knob end of lever 13 transversely to his left and then moves it forwardly, For second speed he pulls the knob end diagonally back, pin |33 moving forward from the first speed position shown by dotted lines in Fig. '7 to the transverse slot where it slides along slot H51) while pin |35 is sliding in slot |10. After the parts are returned to neutral, the operator shifts to third speed by moving the knob toward his right, pin |33 being moved to slot ||5a. Then, as the knob of lever 13 is moved forwardly, pin |35 moves into slot |i1d and pin |33 slides along the rear wall of the slot |5a. High speed is obtained by a rearward diagonal movement of the knob end of lever 13, the lever assuming the position shown by the dot and dash position of Fig. '1. For reverse the knob end of the lever 13 is shifted beyond its neutral position transversely to the left by the operator. The tongues and IDI, I0| lock the forward speed forks and tongue ||3 is rel-eased from the reverse shift mechanism. A rearward movement of the knob end of the lever operates through the bar and lever 69 to shift the collar 5| to reverse driving position, pin |35 moving in slot ||1c.

We claim:

1. In a change speed transmission having gearing elements, a shift lever, a floating lever er1- gaged thereby, shift forks having parts to operably engage the ends of the floating lever, said shift lever and floating lever having a neutral position wherein said forks hold said gearing elements in non-driving positions, mechanism having parts cooperating with said floating lever to impart a transverse movement thereto and also a rocking movement about one end thereof, in response to a movement of the floating lever by a fore and aft movement of the shift lever between its neutral and active positions.

2. The invention defined by claim 1, said mechanism being further constructed to impart a substantially continuous transverse movement tothe floating lever and to reverse its direction of rocking as the floating lever is moved through its neutral position from one extreme position to another whereby a substantially rectilinear movement of the shift lever from one extreme position to another extreme position shifts a first fork from an active to a neutral position and then shifts a second fork from a neutral to an active position.

3. In change speed mechanism, a shift lever, a floating lever engaged thereby adapted to be moved from a first extreme position to a first neutral position and then to a second extreme position, shift forks having parts operably engaging the ends of the floating lever and mechanism constructed to impart a transverse movement and simultaneously to impart successive and opposite pivotal movements to the floating lever whereby a substantial rectilinear fore and aft movement of the shift lever between its extreme positions shifts a first fork from an active to a neutral position and then a second fork from a neutral to an active position, said mechanism also constructed to permit said floating lever to assume a second neutral position in response to a transverse movement of the shift lever, said floating lever then being adapted to be rocked and transversely moved by said mechanism in response to fore and aft movements of the shift lever but in opposite directions whereby reversed directions of movement are imparted tosaid forks and other driving ratios are obtained.

4. In change speed mechanism, a shift lever, a floating lever engaged thereby to be moved from a flrst extreme position to a rst neutral position and to a second extreme position, shift ratio forks having parts operably engaging the ends of said floating lever and mechanism operable to rock said floating lever about fulcra first at one end and then at the other as it is being bodily moved between its extreme positions, said mechanism comprising a plate having opposed cam slots, each slot having a transverse part and forward and rearward extensions, the extensions being substantially rectilinear, inclined from the longitudinal axis and the forward extension of one slot being substantially parallel with the rear extension of the other slot, said floating lever having parts engaged in said slots.

5. In change speed mechanism, a shift lever, a floating lever engaged thereby to be moved from a flrst extreme position to a first neutral position and to a second eXtreme position, shift ratio forks having parts operably engaging the ends of said floating lever and mechanism operable to rock said floating lever about fulcra first at one end and then at the other as it is being bodily moved between its extremeI positions, said mechanism comprising a plate having opposed cam slots, e'ach slot having a transverse part and forward and rearward extensions, the extensions being substantially rectilinear, inclined from the longitudinal axis and the forward extension of one slot being substantially parallel with the rear extension of the other slot, said floating lever having parts engaged in said slots, said plate being mounted for transverse movement, yielding means to bias said plate to one of its positions, means associated with said plate to lock said forks in neutral position when moved against the resistance of said yielding means, and a third fork adapted to be moved by said shift lever and floating lever when said first forks are lockediby said plate.

DEWEY L. MAKER). HARRY E. FIDLER. 

